Horton

Re: Collation versioning

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Douglas Doole <dougdoole@gmail.com>, Christoph Berg <myon@debian.org>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-11-04T20:58:51Z
Lists: pgsql-hackers 
On Tue, Nov 5, 2019 at 4:18 AM Julien Rouhaud <rjuju123@gmail.com> wrote:
> On Mon, Nov 4, 2019 at 11:13 AM Julien Rouhaud <rjuju123@gmail.com> wrote:
> > On Mon, Nov 4, 2019 at 4:58 AM Thomas Munro <thomas.munro@gmail.com> wrote:
> > > Here are some problems to think about:
> > >
> > > * We'd need to track dependencies on the default collation once we
> > > have versioning for that [...]
>
> Another problem I just thought about is how to avoid discrepancy of
> collation version for indexes on shared objects, such as
> pg_database_datname_index.

I didn't look closely at the code, but I think when "name" recently
became collation-aware (commit 586b98fd), it switched to using
C_COLLATION_OID as its typcollation, and "C" doesn't need versioning,
so I think it would only be a problem if there are shared catalogs
that have "name" columns that have a non-type-default collation.
There are none of those, and you can't create them, right?  If there
were, if we take this patch set to its logical conclusion, we'd also
need pg_shdepend.refobjversion, but we don't need it AFAICS.

Commits

  1. Doc: Document known problem with Windows collation versions.

  2. Add collation versions for FreeBSD.

  3. Tolerate version lookup failure for old style Windows locale names.

  4. Track collation versions for indexes.

  5. Add pg_depend.refobjversion.

  6. Remove pg_collation.collversion.

  7. Fix the MSVC build for versions 2015 and later.

  8. Add collation versions for Windows.

  9. Implement type regcollation

  10. Use libc version as a collation version on glibc systems.

  11. Make type "name" collation-aware.